[nocarrier]

Thanks stan_rogers and splat, using local noon plus a clock makes total sense after you described how it works. And I just read a fun Wikipedia node on the history of longitude for good measure too.

https://en.wikipedia.org/wiki/History_of_longitude

[aguynamedben]

There is an excellent book about "the Longitude problem" that details John Harrison and the invention of high precision chronometers: http://www.amazon.com/Longitude-Genius-Greatest-Scientific-P... Great short book for any engineer.